Endoscopic vessel harvesting system components

ABSTRACT

A vessel dissector used in conjunction with an endoscope is provided with a lumen for receiving the endoscope; a blunt dissecting tip provided on a distal end of an elongated cannula permitting tissue dissection while viewing internal body structures via an objective lens of the endoscope; and a vessel severing tool extending through at least a portion of the elongated cannula and translatable longitudinally relative to the elongated cannula, and the vessel severing tool comprises an electrode-carrying member translatable circumferentially within an arcuate slot extending through an outer surface of the vessel dissector, wherein the arcuate slot comprises an inner radius, an outer radius and a central radius, wherein the outer radius is greater than the inner radius and the central radius is located between the outer radius and the inner radius so the arcuate slot provides a uniform opening through which the electrode-carrying member can extend and retract.

This application is a divisional application of U.S. patent applicationSer. No. 15/686,046 (now U.S. Pat. No. 10,299,770 B2) filed on Aug. 24,2017, which is a divisional application of U.S. patent application Ser.No. 11/446,024 (now U.S. Pat. No. 9,770,230 B2), which was filed on Jun.1, 2006. The above-mentioned applications and patents are incorporatedherein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to surgical devices and methods fordissection and removal of blood vessels from a patient's body and, inparticular, to endoscopic vessel harvesting systems, components andmethods.

BACKGROUND OF THE INVENTION

Endoscopic harvesting of vessels is well known in the surgical field andhas been the subject of a great deal of recent technologicaladvancement. Typically, the harvested vessel is used for bypass or as ashunt around an artery that has diminished flow from stenosis or otheranomaly, such as in a Coronary Artery Bypass Grafting (CABG) procedure.Often in CABG, a saphenous vein from the patient's leg is harvested forsubsequent use in the surgery. Other vessels, such as the radial artery,can also be harvested and used in this manner. Vessel harvestinginvolves liberating the vessel from surrounding tissue and transectingsmaller side branches, cauterizing, tying or ligating the vessel at aproximal site and a distal site, and then transecting the vessel at bothsites before it is removed from the body.

Known endoscopic methods and devices for performing vessel harvestingare discussed in detail in U.S. Pat. No. 6,176,825 to Chin, et al., Re36,043 to Knighton, U.S. Pat. No. 6,406,425 to Chin, et al., and U.S.Pat. No. 6,471,638 to Chang, et al., all of which are expresslyincorporated herein by reference. Furthermore, various devices andmethods disclosed in U.S. Pat. No. 5,895,353 to Lunsford, et al., andU.S. Pat. No. 6,162,173 to Chin, et al., and pending patent applicationSer. No. 10/602,490 entitled “Apparatus and Method for Integrated VesselLigator and Transector” are also expressly incorporated herein byreference. Also, commercial vessel harvesting systems sold under thetradename VASOVIEW® Uniport Plus, VASOVIEW® 5, VASOVIEW® 6, andVASOVIEW® 7 are available from Guidant Corporation of Santa Clara,Calif.

Another version of an endoscopic vessel harvesting system is disclosedin U.S. Patent Publication No. 2003/0130674 to Kasahara, et al., filedon Dec. 24, 2002, or and later updated in U.S. Patent Publication No.2005/0159764 also to Kasahara, et al., filed Oct. 27, 2004. In thesesystems, various devices are utilized to first dissect a vein fromsurrounding tissue and then harvest the vein. Each of the devices passesthrough a guide tube of a trocar inserted through a body surface, suchas disclosed in U.S. Pat. No. 6,863,674 also to Kasahara, et al., filedDec. 23, 2002. Certain elements of these and other related patentdisclosures are evident in the VirtuoSaph™ endoscopic vein harvestingsystem (see, www.terumo-cvs.com/products) marketed by TerumoCardiovascular Systems Corp. of Japan.

Despite accepted endoscopic vessel harvesting systems and techniques,there remains a need for systems and components that both make theuser's task less complicated and improve the surgical outcome.

SUMMARY OF THE INVENTION

The present invention provides an endoscopic vessel harvesting systemsuitable for harvesting various target vessels that allows for simpleand convenient operation in a limited space. The invention includesimprovements to various components of vessel harvesting systems each ofwhich can be used with any of the other component improvements. Itshould be understood, therefore, that even if a particular combinationis not explicitly described, any one component can be used with anyother component disclosed herein unless that combination is structurallyimpossible.

In accordance with a first embodiment, the present invention provides avessel dissector that is used in conjunction with an endoscope,comprising an elongated cannula including a lumen therein for receivingthe endoscope, the elongated cannula further housing a passage fordelivery of an insufflation gas therethrough. The vessel dissector hasan input for connecting to a supply of insufflation gas, the input beingin fluid communication with the passage. A port opens near the distalend of the elongated cannula in fluid communication with the passage andout of which insufflation gas is expelled. A fluid barrier covers theport that permits expulsion of insufflation gas from the passage withinthe elongated cannula and prevents ingress of fluid from outside theelongated cannula through the port to the passage.

The port may be formed in the side of the elongated cannula. Desirably,the fluid barrier comprises a tubular member surrounding the distal endof the elongated cannula and covering the port. In one embodiment, thefluid barrier comprises a polymer shield that closes off the port fromthe outside but is flexible so that insufflation gas may escape from thepassage therethrough. In another embodiment, the fluid barrier comprisesa gas-permeable liquid-resistant membrane that permits escape ofinsufflation gas therethrough but prevents entrance of fluid to thepassage.

The vessel dissector may further include a transparent conical tip on adistal end of the elongated cannula that permits an operator of thedissector to dissect tissue while viewing internal body structures viaan objective lens of the endoscope positioned close to the blunt tip.The insufflation gas port may be located at the apex of the conical tip.The vessel dissector may also have a coupling between the distal end ofthe elongated cannula and the transparent blunt tip and a control memberextending through the elongated cannula to enable the user to angle thetip relative to the axis of the elongated cannula. For instance, thecoupling may be an accordion-like flexible interface or sleeve, or aspherical bearing surface,

In accordance with a second embodiment, the present invention provides avessel dissector that is used in conjunction with an endoscope,comprising an elongated cannula including a lumen therein for receivingthe endoscope. A hollow outwardly conical transparent dissecting tip ona distal end of the elongated cannula permits an operator of thedissector to dissect tissue while viewing internal body structures viaan objective lens of the endoscope. The tip comprises a structuregenerally arranged about an axis and having an inner wall thatterminates at a distal end in a shape that tends to reduce glare back tothe objective lens of the endoscope in comparison to a conical innerwall that tapers symmetrically to an apex. For example, the shape of thedistal end of the inner wall of the dissecting tip may be an innertapering surface that terminates at its distal end in a line so as toform an elongated inner corner, an inner surface that tapers downwardtoward its distal end and terminates in a flat surface set at an anglefrom the axis of the tip, or a backward wedge. Desirably, the dissectingtip has a tip diameter and the elongated cannula has a diameter adjacentthe dissecting tip that is between about 50-75% of the tip diameter.

In a more robust system, the vessel dissector may also include a vesselholding tool extending through the elongated cannula and adapted forlongitudinal movement therein, and a vessel severing tool such as atissue welder extending through the elongated cannula and adapted forlongitudinal movement therein. In this embodiment, the dissecting tipincludes apertures for passage of the vessel holding tool and the vesselsevering tool. Preferably, both the vessel holding tool and the vesselsevering tool dock into recesses in the dissecting tip and have exteriorshapes that conform to the conical exterior of the dissecting tip so asto match its shape.

In accordance with a third embodiment, the present invention provides avessel dissector that is used in conjunction with an endoscope. Thevessel dissector is defined by an elongated cannula including a lumentherein for receiving the endoscope. A transparent blunt tip on a distalend of the elongated cannula permits an operator of the dissector todissect tissue while viewing internal body structures via an objectivelens of the endoscope. A wiper clears tissue from the exterior of thetransparent blunt tip. The wiper may be arranged on the elongatedcannula to pivot about an axis to alternately contact and disengage fromthe transparent blunt tip, and a mechanism for rotating the blunt tip.Alternatively, the wiper is arranged on the elongated cannula to contactthe blunt tip and swivel about the axis of the device. Still further,the wiper may be an O-ring wiper fitted over the blunt tip and connectedto an actuation rod that displaces the O-ring wiper longitudinally towipe over the blunt tip. In one embodiment, the wiper is arranged on theelongated cannula to contact the blunt tip and has an energized cuttingelectrode thereon to remove tissue via ablation. Preferably, a handledisposed at a proximal end of the elongated cannula has a thumb leverthereon connected to an actuating rod for displacing the wiper relativeto the transparent blunt tip and clearing tissue therefrom.

In accordance with a fourth embodiment, a vessel harvester used inconjunction with an endoscope comprises an elongated cannula including alumen therein for receiving the endoscope, and a vessel holding toolextending through the elongated cannula and adapted for longitudinalmovement therein. A distal end of the vessel holding tool includes avessel hook and a locking member used to capture a target vessel,wherein the hook is open on one side and extension of the locking membercloses the open side so that the target vessel is completely surroundedand captured therein. A vessel severing tool extends through theelongated cannula for longitudinal movement therein, and has a distaloperative end with structure for severing a target vessel. The vesselholding tool includes a support rod that extends through the elongatedcannula and which is configured to angle laterally at a location closeto the distal end of the tool to enable lateral vessel manipulation andimprove positioning of the vessel severing tool relative to the targetvessel.

Desirably, the support rod is bent out of a plane in which the supportrod lies at a location close to the distal end of the vessel holdingtool such that the distal end angles either toward or away from thevessel severing tool. The support rod may be flexible such that the bendis retracted into the cannula and distal extension of the vessel holdingtool from the end of the elongated cannula displaces its distal endlaterally. A flexible support rod may be surrounded by a rigid hypotubealso adapted for longitudinal movement with respect to the cannula,wherein extension of both the support rod and hypotube from the cannulaand then retraction of the hypotube from around the support rod anglesthe vessel holding tool. Alternatively, the support rod is bent out of aplane in which the support rod lies at a location close to the distalend of the vessel holding tool using an active angling mechanismcontrolled from a proximal end of the elongated cannula.

The vessel hook of the vessel holding tool may include a blunt tapereddistal dissecting surface for blunt dissection of tissue. Further, thevessel hook of the vessel holding tool defines a space therein forreceiving a target vessel, and the locking member may be shaped as alarge wedge to reduce the space within the open vessel hook by about 50%and includes a tapered leading edge that helps prevent pinching of thetarget vessel as the locking member extends.

In accordance with a fifth embodiment, the present invention provides avessel harvester that is used in conjunction with an endoscope,comprising an elongated cannula including a lumen therein for receivingthe endoscope. A vessel severing tool extends through the elongatedcannula for longitudinal movement therein, the severing tool having adistal operative end with structure for severing a target vessel. Avessel holding tool also extends through the elongated cannula forlongitudinal movement therein and has a single support rod that extendsthrough the elongated cannula and a distal end with a vessel hook and alocking member used to capture a target vessel and manipulate it topresent a side branch of the target vessel to the vessel severing tool.The hook is open on one side and extension of the locking member closesthe open side so that the target vessel is completely surrounded andcaptured therein. The locking member extends concentrically from thesingle support rod on one lateral side of the vessel hook, the singlesupport rod therefore reducing endoscopic viewing impediments relativeto more than one support rod.

The support rod may be configured to angle laterally at a location closeto the distal end of the tool to enable lateral vessel manipulation andimproved positioning of the vessel severing tool relative to the targetvessel. Desirably, the vessel hook of the vessel holding tool includes ablunt tapered distal dissecting surface for blunt dissection of tissue.

In accordance with a sixth embodiment, the present invention provides avessel harvester that is used in conjunction with an endoscope,comprising an elongated cannula including a lumen therein for receivingthe endoscope. A vessel severing tool extends through the elongatedcannula for longitudinal movement therein, the severing tool having adistal operative end with structure for severing a target vessel. Avessel holding tool also extends through the elongated cannula forlongitudinal movement therein. The vessel holding tool has a support rodthat extends through the elongated cannula and a distal end with avessel hook and a locking member used to capture a target vessel andmanipulate it to present a side branch of the target vessel to thevessel severing tool. The hook is open on one side and extension of thelocking member closes the open side so that the target vessel iscompletely surrounded and captured therein. The distal end of the vesselholding tool including the hook and locking member are constructed of athin wireform for reduced impediment to endoscopic viewing. Preferably,the thin wireform is formed of metal or plastic wires having a thicknessof between about 0.5 mm and 1.0 mm. Desirably, the support rod isconfigured to angle laterally at a location close to the distal end ofthe tool to enable lateral vessel manipulation and improved positioningof the vessel severing tool relative to the target vessel,

In accordance with a seventh embodiment, the present invention providesa vessel harvester that is used in conjunction with an endoscope,comprising an elongated cannula including a lumen therein for receivingthe endoscope. A vessel severing tool extends through the elongatedcannula for longitudinal movement therein, the severing tool having adistal operative end with structure for severing a target vessel. Avessel holding tool also extends through the elongated cannula forlongitudinal movement therein. The vessel holding tool has a support rodthat extends through the elongated cannula and a distal end with avessel holder used to capture a target vessel and manipulate it topresent a side branch of the target vessel to the vessel severing tool.A damped slip mechanism provided around the support rod of the vesselholding tool permits relative movement between the cannula and thesupport rod if the vessel holder catches on any body structure andgenerates a reaction force in the support rod in opposition to movementof the cannula. For instance, the damped slip mechanism comprises afriction collar surrounding the support rod, or a piston/cylinder/springarrangement that couples movement of the support rod and cannula.

In a preferred embodiment wherein the vessel holder of the vesselholding tool is open on one side and defines a space therein forreceiving a target vessel. A locking member moves to close the open sideof the holder so that the target vessel is completely surrounded andcaptured therein. The locking member is shaped as a large wedge toreduce the space within the open vessel holder by about 50% and includesa tapered leading edge that helps prevent pinching of the target vesselas the locking member moves. Also, the vessel holding tool has improvedvisibility by virtue of a single support rod that extends through theelongated cannula, wherein the locking member extends concentricallyfrom the single support rod on one lateral side of the vessel holder,the single support rod therefore reducing endoscopic viewing impedimentsrelative to more than one support rod. Desirably, the distal end of thevessel holding tool including the holder and locking member areconstructed of a thin wireform for reduced impediment to endoscopicviewing.

In accordance with an eighth embodiment, the present invention providesa vessel harvester that is used in conjunction with an endoscope,comprising an elongated cannula including a lumen therein for receivingthe endoscope. A vessel severing tool extends through the elongatedcannula for longitudinal movement therein, the severing tool has adistal operative end with an open mouth for receiving a target vesselthat automatically accommodates widely varying sizes of vessel, and asevering device associated with the mouth. A vessel holding tool extendsthrough the elongated cannula for longitudinal movement therein, thevessel holding tool having structure used to capture a target vessel andmanipulate it to relative to the vessel severing tool. The mouth of thevessel severing tool preferably accommodates vessels having diametersthat range from between 0.5 and 1.0 mm.

In one embodiment, the mouth has facing vessel contacts that flex apartupon receiving a vessel therebetween. The severing device may havebipolar electrodes disposed to contact a target vessel received withinthe mouth. For instance, the bipolar electrodes comprise wire electrodesarranged in a crossing pattern in the mouth. In another version, themouth has a stepped shape with several progressively smallerintermediate gaps having generally parallel sides that provide regionsof constant width surface contact with the vessel. The intermediate gapsmay have widths in decreasing increments of 1.0 mm. The severing devicemay be a mechanical cutter disposed transverse to a target vesselreceived within the mouth. For efficacy, a fluid conduit terminatesclose to the distal operative end of the vessel severing tool and isadapted to deliver a fluid jet to knock away tissue that may stick tothe distal operative end.

The vessel severing tool may be connected to a control rod and locatedwithin an arcuate slot formed in the elongated cannula, the control rodbeing capable of translating the distal operative end laterally withinthe arcuate slot as well as longitudinally. The mouth of the vesselsevering tool may open to one side of the distal operative end. Thevessel holding tool may includes a support rod that extends through theelongated cannula and is bent out of a plane in which the support rodlies at a location close to the distal end of the vessel holding toolsuch that the distal end angles either toward or away from the vesselsevering tool.

In accordance with a ninth embodiment, the present invention provides avessel harvester that is used in conjunction with an endoscope,comprising an elongated cannula including a lumen therein for receivingthe endoscope. A pair of partial tubular vessel shields extend from thecannula and define a lumen sized to receive a target vessel, the partialtubular vessel shields defining gaps therebetween sized to receive aside branch extending from the target vessel. A tubular cutting elementsized to surround the partial tubular vessel shields and axiallydisplaceable from the cannula, advances to sever any side branchreceived within the gaps while the partial tubular vessel shieldsprotect the target vessel from the severing operation. The vesselsevering tool may be a tubular knife blade. A fluid conduit terminatingclose to the partial tubular vessel shields may be adapted to deliver afluid jet to knock away tissue that may stick to the vessel shields.

In accordance with a tenth embodiment, the present invention provides avessel harvester that is used in conjunction with an endoscope,comprising an elongated cannula including a lumen therein for receivingthe endoscope. A pair of fork-shaped vessel sealing electrodes havingtines are spaced laterally apart so as to create a gap therebetween. Avessel capturing mandible moves within the gap between the electrodes tocapture a target vessel positioned between the tines. A severing blademoves within the gap and sever the target vessel. Desirably, the vesselcapturing mandible has a serrated distal finger to securely capture thetarget vessel within the tines. Both of the vessel capturing mandibleand severing blade may have control rods and angled proximal surfacesthat cam against a distal end of the elongated cannula and displace themtoward one another upon proximal retraction of the control rods. A fluidconduit terminating close to the fork-shaped vessel sealing electrodesmay deliver a fluid jet to knock away tissue that sticks to the sealingelectrodes.

A further understanding of the nature and advantages of the presentinvention are set forth in the following description and claims,particularly when considered in conjunction with the accompanyingdrawings in which like parts bear like reference numerals.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the present invention will become appreciatedas the same become better understood with reference to thespecification, claims, and appended drawings wherein:

FIG. 2A is a perspective view of an endoscopic vessel dissector of theprior art;

FIG. 1B is a perspective view of an endoscopic vessel harvester of theprior art;

FIG. 1C is a perspective view of an access trocar of the prior art;

FIGS. 2A and 2B are side views of the distal end of alternative vesseldissectors of the present invention including articulated dissectingtips;

FIG. 3 is a side view schematically illustrating the possible path ofbodily fluids into the prior art endoscopic vessel dissector of FIG. 1A;

FIGS. 4A and 4B are side views of the distal end of alternative vesseldissectors of the present invention including structures for inhibitingingress of bodily fluids into the dissector cannula;

FIG. 5A is a schematic side view of an endoscopic vessel dissector ofthe prior art passing through body tissue;

FIG. 5B is a schematic side view of an endoscopic vessel dissector ofthe present invention having a narrowed cannula for easier passagethrough body tissue;

FIGS. 6A-6C are longitudinal sectional views through alternativetransparent conical tips for use with endoscopic vessel dissectors ofthe present invention;

FIG. 7 is a schematic sectional view of the distal end of an alternativeendoscopic vessel dissector of the present invention which incorporatestools for harvesting vessels;

FIG. 8 is a perspective view of an endoscopic vessel dissector of thepresent invention having a wiper blade for clearing the distal tip;

FIGS. 9 and 10 are perspective views of the distal tip of twoalternative endoscopic vessel dissectors of the present invention bothhaving tip wiping capabilities;

FIGS. 11A and 11B are schematic side views of an endoscopic vesselharvester of the prior art showing vessel holding and severing toolsextended from the distal end of a cannula;

FIGS. 12A and 12B are schematic side views of an endoscopic vesselharvester of the present invention showing vessel holding and severingtools extended from the distal end of a cannula wherein the vesselholding tool translates laterally for better vessel retraction;

FIG. 13 is a schematic side view of an alternative endoscopic vesselharvester of the present invention wherein a vessel holding toolincludes a tip angled toward the vessel severing tool;

FIGS. 14A-14C are several views of the transverse displacement of analternative vessel holding tool from an endoscopic vessel harvester ofthe present invention;

FIGS. 15A-15B are side and perspective views of an alternative vesselholding tool of the present invention having one connecting rod;

FIGS. 16A-16B are side and perspective views of a low profile vesselholding tool of the present invention formed of thin wire;

FIGS. 17A-17B are partial sectional views of alternative vessel holdingtools of the present invention incorporating a mechanism for preventingvessel avulsion;

FIG. 18 is a side view of the distal end of an alternative vesselholding tool of the present invention having an enlarged locking memberfor better positioning of the vessel;

FIGS. 19A and 19B are schematic views of an alternative vessel severingtool of the present invention having wire electrodes extending into anenlarged vessel-receiving gap;

FIG. 20 is a schematic view of an alternative vessel severing tool ofthe present invention having a stepped vessel receiving gap;

FIGS. 21A-21B are two side views of a vessel severing tool of thepresent invention having movable jaws;

FIG. 22 is a side view of a vessel severing tool of the presentinvention having rotary blades incorporated therein;

FIGS. 23A-23B are two side views of a vessel severing tool of thepresent invention having a movable blade;

FIG. 24 is a schematic view of a vessel severing tool of the presentinvention having a system for clearing tissue therefrom using gas jets;

FIGS. 25A-25B are front and top section views, respectively, of analternative vessel severing tool of the present invention capable oftranslating transversely as well as longitudinally;

FIG. 26 is a schematic front view of an alternative vessel severing toolof the present invention having a tubular cutting element surrounding atubular primary vessel shield;

FIGS. 27A-27B are side elevational and top plan views, respectively, ofa further alternative vessel severing/sealing tool that incorporates amovable mandible for capturing a vessel and a mechanical blade forsevering it;

FIGS. 28A-28B are two schematic views of a side-opening vesselsevering/sealing tool;

FIG. 29 is a longitudinal endoscopic view showing the use of the tool inFIGS. 28A-28B; and

FIG. 30 is a top plan view of an alternative severing tool having a ringand concentric coil bipolar electrode structure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present application provides a number of improvements to prior artvessel harvesting systems. The disclosures herein of various componentparts of vessel harvesting systems should be viewed with the presumptionthat each can work in combination with other components unless stated asbeing mutually exclusive. For example, the various endoscopic vesseldissectors described herein may be utilized in combination with any ofthe endoscopic vessel harvesters. Moreover, any single one componentimprovement described herein may be incorporated into any existingvessel harvesting system, again, unless the structures or functions aremutually exclusive.

Prior Endoscopic Vessel Harvesting System

The three primary components of an exemplary prior art vessel harvestingsystem are seen in the separate views of FIGS. 1A-1C. This particularsystem is representative of one type of prior art vessel harvestingsystems, and many of the improvements described herein will be describedwith direct reference to it. However, as will be understood by one ofskill in the art, any one single improvement to a subcomponent of thevessel harvesting system may, in most cases, be incorporated into othersuch systems. More important, if any single improvement(s) areindependently claimed, the application should not be construed as beinglimited to the system shown in FIGS. 1A-1C. That said, the exemplaryprior art system includes an endoscopic dissector 20 in FIG. 1A, anendoscopic vessel harvester 22 seen in FIG. 1B, and an access trocar 24seen in FIG. 1C.

The endoscopic dissector 20 includes an elongated tube or cannula 30extending between a distal conical tip 32 and a proximal handle 34. Abell-shaped port 36 on a proximal end of the handle 34 receives aconventional medical endoscope 38 which may be fitted with an opticalconnector 40. Although not shown, the elongated shaft of the endoscope38 extends through the entire length of the dissector 20 such that aviewing end terminates in proximity to the conical tip 32, which istypically transparent. It should be understood that vessel harvestingsystems are typically disposable and are packaged and sold separatelyfrom the endoscope which is typically reused. In all cases, however,these endoscopic vessel harvesting systems are designed to accommodateand function with a conventional endoscope, and are therefore claimedaccordingly.

Tubing 42 supplies insufflation gas into an input within the handle 34that opens into an elongated passage within the cannula 30 incommunication with a distal egress port 44. In use, the user inserts thedistal tip 32 and cannula 30 into the body through an access device suchas the trocar 24 seen in FIG. 1C, and into proximity with a targetvessel, such as the saphenous vein in the leg. By pushing the conicaltip 32 along the target vessel under endoscopic vision, the user is ableto grossly dissect connecting tissue from around the vessel.Insufflation gas forced out of the distal port 44 pressurizes thedissected cavity and facilitates viewing and further dissection. After adesired length of target vessel has been separated from surroundingtissue, the dissector 20 is removed from the patient.

Subsequent to vessel dissection, the vessel harvester 22 is insertedthrough the access trocar 24 and into the dissected cavity around thetarget vessel. The vessel harvester 22 also includes an elongated tubeor cannula 50 extending between an open distal end 52 and a proximalhandle 54. Again, a conventional endoscope 38 snaps into a proximalbell-shaped port 56 that includes an axial slot 58 to receive theperpendicularly-extending optical connector 40. As with the dissector20, the elongated shaft of the endoscope passes entirely through thecannula 50 and terminates at a viewing end or objective lens 60 close tothe open distal end 52.

The harvester 22 further includes tools to sever side branches from thetarget vessel while simultaneously closing them off to prevent bleeding.For instance, a holding tool 62 may be used to manipulate the targetvessel so that a severing and sealing tool 64 has clear access to thevarious side branches. Each of these tools may be manipulated bycontrols 66 provided in the handle 54. One of the controls 66 is a thumblever thumb lever that connects to a wiper blade at the distal end ofthe elongated cannula 50 for clearing the objective lens 60 of theendoscope. To facilitate the harvesting operation, an insufflationsystem including tubing 68 may be provided so that gas may be passed outthe open distal end 52 of the cannula 50. Also, electrical wires 70connect to the handle 54 to provide energy for a coagulator incorporatedinto the severing and sealing tool 64. It should be understood that asgenerally described so far, these components of the prior art vesselharvesting system are well known in the art, the present applicationdealing with improvements thereto.

The third main component of the harvesting system is the access trocar24 seen in FIG. 1C. In this embodiment, the trocar includes a mainaccess tube 70 having an angled distal tip 72 and a proximal housing 74.Although not shown, an inner seal such as a diaphragm seal may beincorporated within the housing 74 to provide a gas-tight interface withthe dissector 20 or harvester 22 that passes through the trocar 24. Themain access tube 70 extends through an incision in the body and aspring-biased clip 76 secures the trocar thereto.

Improvements to Dissection Function

FIG. 2A shows the distal end of an alternative vessel dissector 80 ofthe present invention including an articulated dissecting tip 82. Thetip 82 connects to an elongated cannula 84 via an accordion-likeflexible interface or sleeve 86. A pair of pull wires 88 extends throughthe cannula 84 and attaches to points on opposite sides of thedissecting tip 82. By manipulating the pull wires 88, the user can anglethe generally conical tip 82 in either direction within a plane,relative to the axis of the elongated cannula. By rotating the entirecannula 84, a full 360° range of tip movement is obtained. The flexiblesleeve 86 acts like a compression spring and tends to revert the tip 82back to an axial alignment when pull forces are released.

FIG. 2B is another alternative vessel dissector 90 having an articulateddissecting tip 92. As with the dissector 80, the tip 92 connects to thedistal end of an elongated cannula 94 in a manner that enables it to beangled within a plane with respect to the cannula. In this embodiment, aspherical bearing surface 96 provides the interface between the tip 92and cannula 94. A pair of pull wires 98 connected to the tip 92 enablesthe user to angle the tip as desired. A flexible spine of sorts (notshown) may also be provided to provide a force that restores the axialalignment of the tip 92 when pull forces are released.

FIG. 3 is a side view schematically illustrating the possible path ofbodily fluids into an existing endoscopic vessel dissector 100 thatincludes one or more ports 102 near its distal end for insufflation ofgas such as CO₂. That is, a passage is provided within the cannula ofthe vessel dissector 100 to deliver gas from a proximal end thereof tothe ports 112. If fluid is permitted to enter the cannula through theinsufflation ports 102, it may eventually migrate to within thetransparent distal tip and interfere with endoscopic viewing therefrom.

FIG. 4A illustrates the distal end of an alternative vessel dissector110 of the present invention including a small fluid barrier 112extending proximally from the distal tip 114 for inhibiting ingress ofbodily fluids into insufflation ports 116 formed in the side of thedissector cannula. The fluid barrier 112 in this embodiment comprises atubular shield which can be formed from relatively thin medicalplastics. The fluid barrier 112 is desirably flexible enough to permitgas egress from the ports 116 while preventing liquid or solid ingress,much like a reed valve.

FIG. 4B shows an alternative vessel dissector 120 having an alternativefluid barrier 122 surrounding the distal end thereof near the distal tip124. The fluid barrier 122 in this embodiment comprises a tubular porousmembrane that covers the gas insufflation ports 126 in the side of thedissector cannula so that liquid or solid is prevented from enteringthough gas can exit. The membrane 122 is any medically suitablegas-permeable liquid-resistant barrier such as ePTFE made by W.L. Gore.

In a further embodiment, the port from which insufflation gas isexpelled is located not on the cannula body, but on a dissecting tipsecured to the distal end thereof. For example, the dissecting tips 82,92 of FIG. 2A/2B may feature a port from which gas escapes into thesurrounding tissue cavity. Alternatively, a transparent conical tip 32as in FIG. 1A may have a port formed at the distal apex. In each ofthese alternatives, a fluid barrier desirably fills or covers the portto prevent liquid or solid ingress, while permitting gas egress. Formingthe port on the dissecting tip may be advantageous because the gas isexpelled farther distally, and a selection of different tips as desiredmay be coupled to a generic cannula.

FIG. 5A is a schematic side view of an endoscopic vessel dissector 100of the prior art passing through body tissue 104. Insufflation assistsin maintaining the dissected cavity or tunnel, though there may befriction between tissue and the following cannula 106 because of itsequal size relative to the dissecting tip 108.

To help facilitate passage of the cannula through issue, an endoscopicvessel dissector 130 of the present invention seen in FIG. 5B includes anarrowed cannula 132, at least adjacent to a dissecting tip 134 anddesirably along its entire length. The cannula 132 has a diameter thatis smaller than the diameter of the dissecting tip 134, and preferablybetween about 50-75% of the diameter of the dissecting tip 134. A narrowcannula proximal to the dissecting tip improves maneuverability andreduces shaft friction within the dissected tunnel.

FIGS. 6A-6C are longitudinal sectional views through alternativetransparent tips for use with endoscopic vessel dissectors of thepresent invention. Prior transparent dissection tips, such as seen inU.S. Pat. No. 5,980,549 to Chin, et al., include a hollow interior witha front wall tapering to a sharp point, or apex. The outer profileretains a more rounded, blunt configuration for atraumatic dissection.The sharp inner apex helps remove a spot of distortion in the center ofthe visual field.

In addition to distortion, some conical blunt dissection tips made ofclear materials reflect light from the light fibers back to theobjective lens of the endoscope. To address this need, a generallyconical dissection tip 140 in FIG. 6A includes an inner tapering surface142 that terminates at its distal end in a line 144 so as to form anelongated inner corner, or reverse wedge shape. This configuration worksto reduce glare back to the objective lens of the endoscope. In FIG. 6B,a dissection tip 146 includes an inner surface that tapers downwardtoward its distal end and terminates in a flat surface 148 set at anangle from the axis of the tip 146. In this case, incident light isreflected away from the objective lens, which is typically placed alongor near the axis of the tip or dissector cannula. Finally, FIG. 6Cillustrates a dissection tip 150 having an internal taper that ends atits distal-most extent in a backward wedge. This shape helps deflectlight from the fibers outward as opposed to directly backward, thusreducing glare or reflection. All of these shapes have the effect ofreducing incident glare from the light fibers back to the objective lensof the endoscope, thus improving the user's view.

A common technique for vessel harvesting is to provide a separate vesseldissector and vessel harvester, with the devices being inserted one at atime in the body, typically through the access trocar. Such is theconfiguration of the system in FIGS. 1A-1C. However, it is conceivablethat the dissecting and harvesting functions can be combined into asingle device to save time. For instance, FIG. 7 schematicallyillustrates the distal end of an integrated endoscopic vesseldissector/harvester 160 of the present invention having a bluntdissecting tip 162 with apertures or recesses for the harvesting tools.More particularly, a vessel holding tool 164 includes a tapered outersurface to match the dissection tip 162 and is stationed within a recesstherein. Likewise, a vessel severing tool 166 having an outer surfacethat conforms to the dissection tip 162 is retracted into a similarrecess. Each of the vessel holding tool 164 and vessel severing tool 166docks into recesses in the dissecting tip and has an exterior shape thatconforms to the conical exterior of the dissecting tip so as to matchits shape. The distal end of an endoscope 168 is seen extending withinthe clear dissection tip 162. For dissection, the tools 164, 166 areretracted to conform to the conical tip 162. Then, by manipulating thevessel holding tool 164 and vessel severing tool 166 (such as by axialand rotational movement), selected side branches or primary vessels maybe severed and sealed immediately after a section of tunnel around theprimary vessel has been dissected. The vessel dissector/harvester 160 istherefore advanced in stages along the primary vessel performing bothdissection and side branch management.

Another configuration that is contemplated to combine the functions ofthe tissue dissector and vessel harvester is to provide a dissection tipthat can be detached from a cannula which contains harvesting tools. Forexample, any of the conical tips seen in FIGS. 6A-6C may be separablefrom a cannula that houses any of the harvesting tools described below.With such a system the user may alternate between dissection inligation-transection as desired. Furthermore, such a detachable conicaltip may include an opening therethrough to permit CO₂ insufflation.Following dissection, the cone is detached and insufflation may continuethrough the open end of the cannula. Another alternative is to provide atether connecting the removable conical tip to the cannula. In this way,the tip can be detached the remains in close proximity to the distal endof the cannula for reattachment if desired,

Occasionally, fatty or other tissue sticks to the outside of the conicaldissecting tip and prevents clear visualization therethrough. FIG. 8 isa perspective view of an endoscopic vessel dissector 170 of the presentinvention having a wiper blade or finger 172 for clearing the distaldissecting tip 174 of tissue. In this embodiment, the wiper blade 172pivots about an axis 176 at the beginning of the dissecting tip 174, orend of the cannula 178. An actuating rod 180 controlled by a thumb lever182 connects to the wiper blade 172 and permits the user to alternatelyretract and engage the blade with the exterior of the dissecting tip174. The tip 174 rotates about the axis of the cannula 178 when the userturns a knob 184 at the proximal end of the device. The wiper blade 172may be rigid or include a resilient scraper much like a vehicle wiperblade. Various structural details of this arrangement are left out butare well within those skilled in the art of medical device design.Likewise, alternative arrangements are contemplated, such as those shownin FIGS. 9 and 10.

FIGS. 9 and 10 are perspective views of the distal tip of twoalternative endoscopic vessel dissectors of the present invention bothhaving tip wiping capabilities. The dissector 190 in FIG. 9 is similarto the dissector 170 of FIG. 8 in that it includes a wiper blade orfinger 192 for clearing tissue from the conical dissecting tip 194.Instead of the tip rotating, however, the blade 192 swivels about theaxis of the device, such as through its connection with a rotating outersleeve or shaft 196 of the elongated device. Again, details of theactuation of the shaft 196 are not shown, but are easily borrowed orsurmised from existing devices. FIG. 10 illustrates a dissector 200fitted with an O-ring wiper 202 over its conical dissecting tip. Anactuation rod 204 displaces the O-ring wiper 202 longitudinally to wipeclean the dissecting tip. The O-ring wiper 202 may be formed as aloosely-wound metal or plastic spiral to facilitate expansion andcontraction around the tip. Of course, there are numerous otherconfigurations of wipers that may be displaced over the dissecting tip,the present application only illustrating an exemplary selection.

A further alternative to the tip wiping devices in FIGS. 8-10 is to addan energized cutting electrode to the wiper blade to remove tissue viaablation. That is, instead of or in addition to an inert rigid orresilient blade, a wire or bar electrode may be incorporated to enableclearing of more stubborn tissue via electrocurrency. Although aspecific structure is not shown, the reader will understand that any ofthe wiper elements shown in FIGS. 8-10 may represent such an energizedwiper.

Still further, any of the conical tips illustrated herein, including thesimple prior art tip seen in FIG. 5A, may be fitted with a system forclearing adhered tissue using fluid expelled from the cannula. Forexample, an annular opening or a series of separatecircumferentially-spaced openings may be provided between the conicaltip and cannula, and streams of saline expelled from the openings toknock tissue off the tip. Saline is particularly suitable, althoughother fluids such as jets of CO₂ gas maybe used. The design intent wouldbe to port the fluid so that it flowed distally along the surface of thecone using the Coanda effect in which a stream of fluid or gas will tendto hug a convex contour when directed at a tangent to that surface.

Improvements to Vessel Holding Function

Once the target vessel has been exposed, such as with dissection alongits length, endoscopic vessel harvesting involves passing an elongateddevice under visualization along the vessel to sever and seal sidebranches. As mentioned above, numerous such systems are currentlyavailable, including the system seen in FIG. 1A-1C. In that system, avessel holding tool manipulates the target vessel such that the sidebranches are positioned in front of a severing and sealing tool. It isimportant to present both the side branch and target vessel clearly sothat the user does not accidentally cut the target vessel instead of theside branch. Also, it is desirable to retract the target vessel so thatthe side branch can be cauterized as far away from the target vessel aspossible, to minimize risk of damage to the vessel from the cautery tool(thermal spread).

FIGS. 11A and 11B are schematic side views of an endoscopic vesselharvester of the prior art showing a vessel holding tool 210 and acomplementary severing tool 212 axially extended from the distal end ofa cannula 214. The holding tool 210 typically has a hook or othercapturing feature for holding a primary vessel 216. As the deviceadvances, side branches 218 are encountered and the system ismanipulated to place them in line with the severing tool 212. There arecertain drawbacks to this arrangement, in particular the linearextension of the tools 210, 212, rendering them somewhat awkward tomaneuver for proper positioning of the side branches 218.

FIGS. 12A and 12B are schematic side views of an endoscopic vesselharvester 220 of the present invention showing a vessel holding tool 222and a severing tool 224 extended from the distal end of a cannula 226.To more easily accomplish straightening of the side branches 218 in linewith the severing tool 224, the vessel holding tool 222 translateslaterally. As seen in FIG. 12B, the effect of angling the holding tool222 radially outward is to facilitate advancement of the tool along theprimary vessel 216 as well as to straighten the side branch 218 for moreeffective cutting with the severing tool 224. A comparison of FIGS. 11Aand 12A shows the increase in spacing between the holding and severingtools, which exposes a greater length of side branch. The holding tool222 can be displaced laterally as shown by simply mounting it on acurved or bent actuation rod, or via an angling mechanism, not shown. Inthe case of a curved or bent support rod, the rod may be flexible so asto retract within the cannula, and the farther the tool 22 extends thegreater the lateral displacement. In general, the vessel holding tool222 includes a support rod that extends through the elongated cannula226 and which is angled or is configured to angle laterally at alocation close to the distal end of the tool.

FIG. 13 is a schematic side view of an alternative endoscopic vesselharvester 230 of the present invention wherein a vessel holding tool 232includes a tip angled toward the vessel severing tool 234. In this way,the holding tool 232 can position the primary vessel 216 in line withthe severing tool 234. Ultimately, the primary vessel 216 will besevered at at least one end after having been separated from itsconnecting side branches. The holding tool 232 facilitates this step. Itis conceivable that the harvesters 220 and 230 can be combined such thatthe vessel holding tool may alternately be angled away from the severingtool, as seen in FIG. 12A, and toward the severing tool, as seen in FIG.13. In other words, an articulating vessel holding tool may be providedthat has a support rod extending through the cannula which is configuredto articulate laterally at a location close to the distal end of thetool and enable different angulations depending on the situation.

FIGS. 14A-14C are several views of the transverse displacement of analternative vessel holding tool 240 upon extension from the cannula 242of an endoscopic vessel harvester of the present invention. In thisembodiment, the holding tool 240 mounts on the end of an elasticwireform 244 having a bend 246. When retracted, the wireform 244straightens within the delivery channel 248. As the tool is extended,the bend 246 eventually clears the end of the channel 248 causinglateral displacement of the holding tool 240.

Another way to enable angling of the distal end of the vessel holdingtool is to provide a flexible support rod or wireform and surround itwith a rigid hypotube. Both structures may longitudinally extend fromthe mouth of the cannula, and then retraction of the hypotube fromaround the wireform angles the vessel holding tool. In this embodiment,greater maneuverability of the vessel holding tube is provided as it maybe angled at various axial locations rather than immediately as it exitsthe cannula.

In a further advantageous feature, the vessel hook of the vessel holdingtool may incorporate a tapered blunt distal dissecting surface for bluntdissection of tissue. The term “blunt” surface in this context means onewithout sharp points or corners and with some degree of taper tofacilitate division or partition of tissue planes. For example, theconical tips described herein are considered blunt, and as a rule do nothave sharp points. The more rectilinear tissue holders of the prior art,however, are too blunt and not well suited for tissue dissection.

It is very important to minimize obstructions in the field of view—themore the device blocks the user's view of the tissue, the greater therisk of avulsions and cautery mistakes. FIGS. 15A-15B are side andperspective views of an alternative vessel holding tool 250 of thepresent invention that has a lower profile than previous tools and thusprovides greater visibility of its operation. With reference back toFIG. 1B, the holding tool 62 of the prior art includes two rods orsupports that extend distally from the cannula 50. These two rodspresent solid viewing obstacles interposed between the endoscopeobjective lens and the actual vessel holding operation. Desirably theseobstacles are minimized.

In one such lower profile holder, the vessel holding tool 250 has asingle main rod or support 252 extending distally from the distal end ofthe cannula 254 that carries a vessel hook 256. The hook 256 is shapedto partially surround the primary vessel and manipulate it to present aside branch to an associated vessel severing tool (not shown). FIG. 15Billustrates the extension of a locking member 258, which can be, forexample, a concentric or telescoping extension of the main rod 252. Thehook 256 may be substantially C-shaped so as to partially surround thevessel, and the extension of the locking member 258 closes the remainingopen side so that the vessel is completely surrounded and capturedtherein. In this way, a vessel may be securely held by the holding tool250 without risk of dislodgment yet the view from the objective lens ismaximized by removal of one of the support rods,

FIGS. 16A-16B illustrate a further vessel holding tool 260 of thepresent invention formed of thin wire, also to reduce its profile,reduce impediments to endoscopic viewing, and thus increase visibilityand accuracy of the operation. The tool 260 extends from the cannula 262and includes a hook portion 264 formed of a single wire, and atranslating locking member 266 formed of another wire or pin. Again,with the locking member 266 extended the holding tool 260 completelyencloses the vessel for manipulation and severing. Although there aretwo support rods extending from the cannula, they are extremely thin andpresent a minimum viewing obstacle to the objective lens. Desirably, theholding tool 260 is formed of metal or plastic wires having a thicknessof between about 0.5 mm and 1.0 mm.

FIG. 17A is a partial sectional view of a vessel holding tool 270 of thepresent invention incorporating a mechanism for preventing vesselavulsion. These types of vessel holding tools are used to hook theprimary vessel and move down its length, occasionally stopping to severside branches. If the tool is moved too fast or too hard when a sidebranch is reached, damage can occur. The tool 270 includes a hookportion 272 that is mounted on the end of a displacement rod 274extending from the cannula 276. Within the cannula 276, the rod 274passes through a friction collar 278 that acts as a damped slipmechanism between the hook portion 272 and the cannula 276. That is, ifthe hook portion 272 experiences resistance as it travels down thelength of the primary vessel, further movement of the cannula 276 willnot further pull or push on the vessel, but instead will cause dampedrelative movement between the cannula and the hook portion.

In a similar manner, FIG. 17B shows a vessel holding tool 280 with ahook portion 282 mounted on a displacement rod 284 extending from acannula 286. A slip mechanism 288, in this case a piston/cylinder/springarrangement, permits damped relative tool/cannula movement in case thehook portion catches on any body structure and generates a reactionforce in the displacement rod 284 in opposition to movement of thecannula 286. Of course, the two examples of FIGS. 17A and 17B are merelyexemplary and other clutch mechanisms performing a similar function canbe substituted.

Finally, FIG. 18 illustrates still another vessel holding tool 290 ofthe present invention having an enlarged locking member 292 for betterpositioning of the vessel 294. That is, the vessel 294 is first retainedwithin the hook portion 296 then a locking member 292 is axiallyextended to capture it. Earlier locking members were thin rods or pinsthat left a relatively large space within the mouth of the hook portion296, and thus especially smaller vessels could easily move around. Inthis embodiment, the locking member 292 is shaped as a large wedge thatlimits the space in which the vessel 294 is held and thus increases itsstability prior to the side branch severing operation. In terms ofrelative size, the locking member 292 when extended desirably reducesthe space within the mouth of the hook portion 296 by about 50%. Thetapered leading edge helps prevent pinching of the vessel as the lockingmember 292 extends.

Improvements to Vessel Severing Function

Numerous instruments are known which coagulate, seal, join, or cuttissue, and which are suitable, for example, for severing a targetvessel from surrounding side branches and securing the separated ends tostanch bleeding. Such devices typically comprise a pair of tweezers,jaws or forceps that grasp onto and hold tissue therebetween. Thedevices may operate with a heating element in contact with the tissue,with an ultrasonic heater that employs frictional heating of the tissue,or with a mono- or bi-polar electrode heating system that passes currentthrough the tissue such that the tissue is heated by virtue of its ownelectrical resistance. The devices heat the tissue to temperatures suchthat the tissue is either “cut” or “sealed”, as follows. When tissue isheated in excess of 100° Celsius, the tissue disposed between thetweezers, jaws or forceps will be broken down and is thus, “cut”.However, when the tissue is heated to temperatures between 50° to 90°Celsius, the tissue will instead simply “seal” or “weld” to adjacenttissue. Monopolar and bipolar probes, forceps or scissors use highfrequency electrical current that passes through the tissue to becoagulated. The current passing through the tissue causes the tissue tobe heated, resulting in coagulation of tissue proteins. In the monopolarvariety of these instruments, the current leaves the electrode and afterpassing through the tissue, returns to the generator by means of a“ground plate” which is attached or connected to a distant part of thepatient's body. In a bipolar version of such an electro-surgicalinstrument, the electric current passes between two electrodes with thetissue being placed or held between the two electrodes as in the“Kleppinger bipolar forceps” used for occlusion of Fallopian tubes. Anew development in this area is the “Tripolar” instrument marketed byCabot and Circon-ACMI which incorporates a mechanical cutting element inaddition to monopolar coagulating electrodes. A similar combined sealingand mechanical cutting device may also be known as a tissue “bisector,”which merges the terms bipolar cautery and dissector. One tissuebisector is packaged for sale as an element of the VASOVIEW® 6 vesselharvesting systems by Guidant Corporation of Santa Clara, Calif. Inultrasonic tissue heaters, a very high frequency (ultrasonic) vibratingelement or rod is held in contact with the tissue. The rapid vibrationsgenerate heat causing the proteins in the tissue to become coagulated.Conductive tissue welders usually include jaws that clamp tissuetherebetween, one or both of which are resistively heated. In this typeof instrument, no electrical current passes through the tissue, as isthe case for monopolar or bipolar cautery,

It should be understood that any of these prior instruments for severingand/or sealing vessels, or those described below, may be combined withthe various components of the vessel harvesting systems describedherein. It should also be understood that various configurations ofmonopolar, bipolar, or other type of electrodes may be provided on thevessel severing/sealing tools described below. Those of skill in the artwill understand that the particular shape and size of the electrodes,and their arrangement with respect to other electrodes, will dictate thepower requirements and operational constraints. Further, someembodiments described herein may work better with one or other type ofelectrodes or heating elements, though such optimal permutations willnot be exhaustively described.

One important function of any severing tool is to manage vessels ofdifferent sizes without extra effort on the part of the user. This isparticularly important for bipolar cautery tools which must realize goodtissue contact with both electrodes for optimum performance. For fixedelectrodes (such as the “bisector” described above), small vessels aremore difficult to cauterize; users are taught to position the vesselbetween the bisector electrodes, and then to rotate the bisector toensure good contact with both electrodes. Merely decreasing the distancebetween the electrodes for better contact may prevent use on largervessels. Moveable electrodes, or jaws, are on solution but require someadditional effort to avoid clamping too hard on the vessel, which mayresult in damage thereto.

FIGS. 19A and 19B are schematic views of an alternative vessel severingtool 300 of the present invention having two wire electrodes 302overlapping across a large gap G defined by a mouth for receiving avessel. In contrast with some earlier devices, the gap G is large enoughto receive both the side branches and the primary vessel, preferablybetween about 4.0 mm and 6.0 mm, more preferably about 6.0 mm. The wireelectrodes 302 that overlap in a crossing pattern across the gap G areresilient and flex to automatically accommodate widely varying sizes ofvessel. In this context “accommodate” means to contact opposite sides ofthe vessel. This is especially important to ensure good contact withvery small vessels. The vessel severing tool 300 desirably accommodatesvessels having diameters that range from between 0.5 mm and 6.0 mm. In avariation of the embodiment of FIGS. 19A and 19B, a vessel severing toolhas a mouth defined by facing vessel contacts that flex apart uponreceiving a vessel therebetween, though the contacts may not beelectrodes. Any cutting tool may be combined with a variably-sized mouthto secure different sized vessels.

Desirably, the wire electrodes are made of stainless steel and have awire thickness of between about 0.5 mm and 1.0 mm so that they easilyflex to permit a vessel to move farther into the gap than if they weremore rigid and thus ensure good current contact with the vessel. Also,as seen in FIG. 19B, the wire electrodes 302 are set at different radialdistances from the central axis of the tool out of contact with eachother, thus providing the separation needed for bipolar coagulation. Onedistinct advantage of the vessel severing tool 300 over prior designs isits ability to automatically accommodate varying sizes of vessel. Thatis tools having movable jaws, for example, can adapt to various vesseldiameters but only upon careful user manipulation. The tool 300 thusspeeds up the entire vessel harvesting operation, which may involveseverance of numerous vessels,

FIG. 20 is a side view of an alternative vessel severing tool 310 of thepresent invention having a stepped vessel-receiving mouth 312. Thestepped shape of the mouth 312 accommodates a wider range of vesselsizes while ensuring good contact with tissue cautery electrodes (notshown) provided, for example, on opposite sides of the mouth. Incontrast to a fixed V-shaped gap, the stair-stepped shape of the mouth312 presents several progressively smaller intermediate gaps withgenerally parallel sides that provide regions of constant width surfacecontact with the vessel. Also, the step to the next smaller intermediategap contacts the vessel. This “bracketing” of the vessel helps ensure agood seal without the risk of excessive pinching. The vessel severingtool 300 desirably accommodates vessels having diameters that range frombetween 0.5 mm and 6.0 mm. In one embodiment, the mouth 312 of thevessel severing tool 300 defines intermediate gaps having widths indecreasing increments of 1.0 mm, for example 6-5-4 mm, or 5-4-3 mm.

Although immovable severing/sealing tools may prove suitable in certainapplications, often it is desirable to apply certain amount of pressureto the vessel with movable jaws, for example. FIGS. 21A-21B illustrate avessel severing tool 320 of the present invention having jaws 322 thatare resiliently biased away from one another and which can be partiallyclosed. The jaws 322 may carry bipolar or monopolar electrodes. A pullwire or control rod 324 connects to a closure ring 326 and enables axialdisplacement thereof for closing the jaws 322, as seen in FIG. 21B.Visualization of the severing/sealing operation then enables the user tovary the extent of closure of the jaws 322, and thus the magnitude ofpressure applied. The jaws 322 cannot completely close and have aminimum gap therebetween as see in FIG. 21B of between about 0.5 mm and1.0 mm. This minimum is calibrated so that the tool 320 accommodateseven the smallest expected vessels, yet excessive clamping of even muchlarger vessels is reduced because there is no contact between the jaws322.

FIG. 22 is a side view of a vessel severing tool 330 having stationeryjaws 332 and rotary blades 334 incorporated thereon. The blades 334 maybe connected to electric power and function as cutting electrodes, ormay be inert knife blades, that work in conjunction with separatesealing electrodes (not shown) provided on the jaws 332. Thisconfiguration removes the need for providing electrodes that performdual severing and sealing functions, which frees the designer tooptimize the sealing electrodes.

FIGS. 23A-23B are two side views of a vessel severing tool 340 having amovable blade 342 that desirably works in cooperation with electrodes(not shown) that seal the cut vessel. A control rod 344 connects todisplace the blade 342 toward an anvil 346 provided on a hook portion348 of the tool 340. The blade 342 and cooperating anvil 346 areslightly angled as shown to sever the vessel with a shearing action. Amechanical cutter such as this may be desirable in contrast toelectrocautery transection which can be time-consuming, may inflictthermal damage on the tissue, and may not be entirely effective.

FIG. 24 schematically illustrates a vessel severing tool 350 having asystem for clearing tissue therefrom using gas jets. Occasionally, therepeated application of heat or electricity to tissue creates stickingor burning of the tissue to the electrodes. One means to resolve thisproblem is to provide tubing 352 extending adjacent a severing/sealingtool 354. The tubing 352 terminates close to the electrodes or cuttingblades of the tool 354 and jets of gas such as CO₂ may be expelled fromthe open ends or from special nozzles to knock tissue off the tool. CO₂is particularly suitable because it is already used for insufflation ofthe body cavity, although other fluids such as saline may also be used.

FIGS. 25A-25B are front and top section views, respectively, of analternative vessel severing tool 360 capable of translating transverselyas well as longitudinally. An electrode-carrying member 362 translatescircumferentially within an arcuate slot 364, and may be actuated by acontrol rod 366. This arrangement greatly enhances the maneuverabilityof the tool and consequently the options for the user.

In FIG. 26, a severing/sealing tool 370 shown from its front end withinan insufflated tunnel 372 includes a cannula having a pair of partialtubular vessel shields 374 extending therefrom around a primary vessel376. The gaps between the shields 374 accommodate side branches 378 fromthe primary vessel 376. A tubular cutting element 380 that may beaxially displaced from the cannula surrounds the shields 374. The userpositions the shields around a vessel 376 with the side branches 378 asshown, and then advances the cutting element 380. The shields 374protect the vessel 376 and ensure adequate stump length of thetransected branches 378. The cutting element 380 may be a tubular knifeblade or an electrode designed to cut.

FIGS. 27A-27B are side and top views of a vessel severing/sealing tool400 that incorporates several moving parts. The tool 400 includes a pairof fork-shaped electrodes 402 spaced laterally apart so as to create agap within which moves a severing blade 404. A vessel capturing mandible406 also moves within the gap between the electrodes 402. In use, avessel 408 is seen positioned within the tines of the fork-shapedelectrodes 402 and prior to capture by the mandible 406. The mandible406 has a serrated distal finger to securely capture the target vesselwithin the tines. Upward movement of the mandible traps the vessel 408at which time energy may be applied by the electrodes 402 to begin thecoagulation process. Subsequently, the blade 404 actuates downward andsevers the vessel 408. Mechanisms for moving both the blade 404 andmandible 406 are not shown, although both have angled or arcuateproximal surfaces that can be utilized to cam against a delivery cannulaand displace the elements toward one another upon their proximalretraction using a control rod, for example.

FIGS. 28A-28B are two schematic views of a vessel severing/sealing tool420 incorporating a side-opening cutter/sealer 422. In the enlarged viewof FIG. 28B, the cutter 422 comprises an upper electrode 424 and a lowerelectrode 426 separated across a slot 428. The upper and lowerelectrodes 424, 426 may be bipolar, and the slot 428 may accommodate aknife blade or other such cutting device. FIG. 29 is an endoscopic viewshowing the use of the tool 420 severing a side branch 430 from aprimary vessel 432.

Finally, FIG. 30 is a top plan view of an alternative severing tool 440which has a first ring-shaped electrode 442 extending from a cannulastructure 444, and the second coil-shaped electrode 446 concentricallyarranged around the first electrode.

While the invention has been described in its preferred embodiments, itis to be understood that the words which have been used are words ofdescription and not of limitation. Therefore, changes may be made withinthe appended claims without departing from the true scope of theinvention.

What is claimed is:
 1. A vessel dissector that is used in conjunction with an endoscope, comprising: an elongated cannula including a lumen therein for receiving the endoscope; a blunt dissecting tip provided on a distal end of the elongated cannula that permits an operator of the vessel dissector to dissect tissue while viewing internal body structures via an objective lens of the endoscope; and a vessel severing tool extending through at least a portion of the elongated cannula, wherein the vessel severing tool is translatable longitudinally relative to the elongated cannula, and wherein the vessel severing tool comprises an electrode-carrying member that is translatable circumferentially within an arcuate slot extending through an outer surface of the vessel dissector, wherein the arcuate slot comprises an inner radius and an outer radius and a central radius, wherein the outer radius is greater than the inner radius and the central radius is located halfway between the outer radius and the inner radius so that the arcuate slot provides a uniform opening through which the electrode-carrying member is controllable to extend and retract, wherein the electrode-carrying member has an arcuate cross section, and the arcuate cross section of the electrode-carrying member matches an arc of the central radius and movement of the electrode-carrying member in the arcuate slot is constrained to follow the arc of the central radius.
 2. The vessel dissector of claim 1, wherein the vessel severing tool further comprises a control rod disposed to actuate the electrode-carrying member.
 3. The vessel dissector of claim 2, wherein the blunt dissecting tip has a central axis and the arcuate slot extends along a longitudinal axis that is offset from the central axis of the blunt dissecting tip.
 4. The vessel dissector of claim 1, wherein the electrode-carrying member comprises bipolar electrodes.
 5. The vessel dissector of claim 4, wherein the vessel severing tool further comprises a control rod disposed to actuate the electrode-carrying member.
 6. The vessel dissector of claim 1, wherein the blunt dissecting tip has a central axis and the arcuate slot extends along a longitudinal axis that is offset from the central axis of the blunt dissecting tip.
 7. A vessel dissector that is used in conjunction with an endoscope, comprising: an elongated cannula including a lumen therein for receiving the endoscope; a blunt dissecting tip provided on a distal end of the elongated cannula that permits viewing of internal body structures while an operator of the vessel dissector dissects tissue with the blunt dissecting tip; and a vessel severing tool extending through at least a portion of the elongated cannula, wherein the vessel severing tool is translatable longitudinally relative to the elongated cannula, and wherein the vessel severing tool comprises an electrode-carrying member that is translatable circumferentially within a curved slot extending through an outer surface of the vessel dissector, wherein the curved slot is defined by a first wall having an inner radius, a second wall having an outer radius, a third wall connecting one end of the first wall to one end of the second wall, and a fourth wall connecting a second end of the first wall to a second end of the second wall, wherein the outer radius is greater than the inner radius and a central radius is located midway between the outer radius and the inner radius so that the curved slot provides an opening through which the electrode-carrying member is controllable to extend and retract, wherein circumferential translation of the electrode-carrying member is limited to a path extending along only the central radius.
 8. The vessel dissector of claim 7, wherein the electrode-carrying member has an arcuate cross section that matches an arc of the central radius.
 9. The vessel dissector of claim 8, wherein the vessel severing tool further comprises a control rod disposed to actuate the electrode-carrying member.
 10. The vessel dissector of claim 7, wherein the blunt dissecting tip has a central axis and the curved slot extends along a longitudinal axis that is offset from the central axis of the blunt dissecting tip.
 11. The vessel dissector of claim 7, wherein the electrode-carrying member comprises bipolar electrodes.
 12. The vessel dissector of claim 7, wherein the curved slot is an arcuate slot.
 13. The vessel dissector of claim 12, wherein the arcuate slot has a uniform width.
 14. The vessel dissector of claim 7, wherein the curved slot is a bow-shaped slot that has a uniform width.
 15. The vessel dissector of claim 7, wherein the curved slot has a uniform width.
 16. The vessel dissector of claim 7, wherein the blunt dissecting tip has a central axis and the curved slot extends along a longitudinal axis that is offset from the central axis of the blunt dissecting tip, and wherein the curved slot has a uniform width. 